Advisory Operations Center • Hydrologic Forecast Unit

Flash Flood Risk and Precipitation Impact Planner

Source Grounding: “Elevated flash flood threats were issued for parts of the Midwest and Southwest late Tuesday afternoon through Wednesday, potentially impacting millions from Illinois to Texas to Arizona.” — ABC News

Advisory Scenarios:
Hydrologic Inputs Continuous Dynamic Engine
Rainfall Intensity 2.4 in/hr
Sustained cell convective precipitation rate
Storm Duration 6 hrs
Consecutive storm cell transit window
Soil Saturation Antecedent 78%
Antecedent moisture conditions limiting ground absorption
Urban Imperviousness 65%
Paved surfaces, concrete culverts, and structural footprint
At-Risk Population Exposed 14.2M
Municipal corridor populations in the path of threat cells
Hydro-Meteorological Telemetry Midwest & Southwest (IL, TX, AZ)
Operational Flood Alert Status
Severe Flash Flood Warning
Catastrophic rapid-onset runoff with severe infrastructure breach expected in low-lying corridors.
Total Precip 14.4 cumulative inches
Runoff Coeff (C) 0.72 rational method
Estimated Runoff 10.37 effective runoff in.
Drainage Capacity Overwhelmed (142% of baseline) baseline cap: 7.30 in.
Hydrograph: Hyetograph & Runoff Volume Curve Hourly Accumulation Model
Target Corridor Vulnerability Assessments
Illinois Basin High Risk
Saturated agricultural catchments & metropolitan stormwater sewers at critical limit.
Texas Hill Country Severe Risk
Limestone topography and rapid ravine water gathering create severe flash flood risks.
Arizona Desert Arroyos Elevated Risk
Dry washes and baked caliche clay accelerate sudden high-velocity wall-of-water flash floods.
Emergency Response & Evacuation Protocols
Export Pipeline: Ready
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